MoSCoW Method

When managing a project, it is important to develop a clear understanding of the customers' requirements and their priority. Many projects start with the barest headline list of requirements, only to find later the customers' needs have not been fully understood.

Once there is a clear set of requirements, it is important to ensure they are ranked. This helps everyone (customer, project manager, designer, developers) understand the most important requirements, in what order to develop them, and those that won't be delivered if there is pressure on resources.

So what is the best method for creating a prioritised list of requirements?

The MoSCoW method can help. MoSCoW stands for must, should, could and would:

M - Must have this requirement to meet the business needs.

S - Should have this requirement if possible, but project success does not rely on it.

C - Could have this requirement if it does not affect anything else in the project.

W - Would like to have this requirement later, but it won't be delivered this time.

The O's in MoSCoW are added to make the acronym pronounceable, and are often left in lowercase to show they don't stand for anything.

MoSCoW as a prioritisation method is used to decide which requirements must be completed first and which must come later or will not be completed at all.

Unlike a numbering system for setting priorities, the words mean something and make it easier to discuss what's important. The must requirements need to provide a coherent solution, and alone lead to project success.

The must requirements are non-negotiable and have to be delivered. Failure to deliver even one of the must requirements will likely mean the project has failed.

The project team should aim to deliver as many of the should requirements as possible. Could and would requirements are 'nice to have' and do not affect the overall success of the project. Could requirements are the first to go if the project timeline or budget comes under pressure.

To deliver a successful project, it is essential that a clear set of prioritised requirements are agreed with the customer, alongside the overall objective, quality, timescale and budget. The recommended method for setting priorities is MoSCoW.

MoSCoW was developed by Dai Clegg of Oracle UK in 1994, and has been made popular by exponents of the Dynamic Systems Development Method (DSDM).

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I don't think it really matters whether it is Won't or Want as long as the intent is clear. It is not worth debating which it should be. Won't, want and would are all used and quoted depending on where you look. Personally, I like would, as in, "I would like to have this requirement, but will leave it out this time for consideration at a later date".

The PMBOK has not defined this anywhere, and it isn't in the PMI lexicon either.

Must, Should, Could, Would is the "all positive" project manager.

Must, Should, Can't, Won't is the "all negative" project manager.

Must, Should, Could, Won't is the "balanced" project manager.

I prefer the balanced approach as it allows you to define some things that have been defined as 'out of scope', while still giving a middle ground of things that you could decide to include in the project.

For requirements prioritization, BABOK says 'W' is for 'Won't', not 'Would' or 'Want' but not necessarily everybody follows the BABOK, so I guess 'Would' would work for some organizations. As long as it is clearly defined what the expectation is and what 'W' stands for, I don't think it's an issue.